The present invention relates generally to power transmitting systems for motor vehicles. More specifically, the invention relates to a hydraulic coupling system.
Power transmitting systems for motor vehicles that distribute torque between the front and rear wheels are known. In some systems, either the front or rear wheels are the primary drive wheels, and the other set are the secondary drive wheels for providing additional traction needed in certain vehicle operating conditions. In these systems, most or all of the torque is transmitted to the primary drive wheels under normal driving conditions. However, when the system detects slippage of the primary drive wheels, a clutch mechanism couples the secondary drive wheels to the primary drive wheels so that a portion of the torque is transmitted to the secondary wheels.
In some vehicles, the torque transfer devices use a wet clutching mechanism to transfer torque between the left and right wheels or between the front and rear wheels. The performance of these wet clutching devices can degrade when subjected to repeated engagement duty cycles with high loads because of the significant generation of heat created through friction in the clutch.